A digital micromirror device is known as a reflective image display device mounted on a projector. The digital micromirror device has an image display surface composed of a plurality of small micromirrors and controls tilting of each mirror surface on the image display surface to modify illumination light in intensity to form an image.
A reflective image display device such as a digital micromirror device generates unnecessary light referred to as OFF light which is not used for projecting an image. For example, in a three-chip (multi-channel) type projector including a color decomposition/compositing prism and three reflective image display devices, OFF light processing is performed by adjusting the color decomposition/compositing prism to be high in level.
Japanese Laid-Open Patent Publication No. 2012-247778 (Patent Document 1) relates to a projection lens and a projector having a magnification changing function, and discloses an invention relating to a projecting zoom lens most suitable for achieving a large magnification changing ratio and a projector using the same.